51 Sky’s Up meet the Moon I t’s a steady presence in all of our lives, but few people take the time to truly get to know Earth’s closest neighbor. In this recurring feature, accomplished astronomer and astrophotographer Dr. Howard Eskildsen will take readers on a quadrant by quadrant journey across the luminous face of the Full Moon. Through his images and words, Eskildsen will explore the legions of geological formations that give the Moon its distinct personality. His indepth information will give context to the features that pop to life when one views our oft romanticized satellite through a telescope or other optical aid. Over the next few pages, the impacts of volcanoes, meteors and other forces will be revealed in detail. From its contribution to our tides to the artistic inspiration it provides, the Moon’s influence on Earth is profound, and it deserves a deeper look. “The Moon is a wonderful friend and companion to the Earth and its residents. Hardly a day goes by that someone does not hear me say, ‘Oh! Look at the Moon.’ It is like Earth’s little brother, and a rocky soul mate to all who dwell here.” — Howard Eskildsen
Wow, saucers on the Moon! But theses saucers do not fly or carry little green creatures from outer space. Rather, they are depressions in the floor of the 153 km crater Ptolemaeus that reveal secrets about the early history of the moon. They can be seen only at very low sun angles and appear almost soft and velvety. One prominent saucer can be seen just above Ammonius on the quadrant image and others can be detected in the Ptolemaeus image. What are they and what happened? Ptolemaeus is an ancient crater, thought to be over 3.9 billion years old, that formed during an era of intense cratering. It has been battered and scarred by later impacts and by distant basin-forming collisions. Early in its lifetime many craters pocked its original floor leaving depressions that were later coated by “fluidized ejecta,” the gritty slurry of rocks and dust violently expelled in the formation of a gigantic impact basin, perhaps 3.85 billion years ago. Albategnius, Klein, Hipparchus and other craters on the quadrant image have similar ejecta fill and some have saucer-like depressions as well. Ammoinus, the only crater formed in Ptolemaeus after the basin-forming catastrophe, was spared since it arrived nearly 3 billion years later! Scars between Herschel and Gylden point accusingly towards Mare Imbrium, hundreds of miles to the northwest, as the source of ejecta sculpturing. Similar scars can be seen on the southeast rim of the badly battered Hipparchus. Its southwestern wall has been obliterated by younger local impacts, and it is so worn that it is difficult to detect unless the sun is at a low angle. The larger craters on the image are all scarred and much older than the smaller craters. Early in the history of the moon large space rocks battered the surface of the moon, but the cratering rate fell off as the objects were depleted. After the Imbrium impact about 3.85 billion years ago cratering events became less common and the impacting objects smaller. Hence most of the younger craters are smaller and widely scattered over the ancient moonscape. Well-preserved Herschel and Horrocks, 41 km and 30 km diameter respectively, are considered “Eratosthenian” in age and may range in age from 3.2 to 1.1 billion years old. The youngest craters, Ammonius, Pickering, and a few other unnamed craters scattered about the image are “Copernican” in age; less than 1.1 billion years old. Other interesting objects include Rima Flammarion and Rima Oppolzer, which are surface fractures with the dropped floors between the fracture walls and are known as grabens. Near Muller, a crater chain crosses diagonally for a short distance. It was formed by an object — possibly a comet — that fragmented prior to impact Quadrant 48: 52 Sky’s Up Craters dotted with saucers, scars — Images and text provided by Howard Eskildsen The ancient Ptolemaeus crater is dotted with depressions.
53 Sky’s Up creating a series of craters. Like the Rosetta Stone, the craters and scars across this tortured landscape reveal an ancient past, filling in details that have been erased on Earth by erosion and crustal motion. Our solar system endured a violent distant past before sweeping most of the space debris from the surroundings of the planets and settling into the relative quiescence that we enjoy today.
54 Sky’s Up What a mess! This part of the Southern Highlands of the moon shows an ancient, crater-saturated surface with rubble and scars from a violent past. The only smooth areas seem to be from dusty fill as seen in the Cayley Plains. But a chaotic moonscape is a geologist’s dream, and it was here that Apollo 16 made the only lunar highlands landing. They thought they knew what to expect, but boy were they wrong! The origin of lunar craters was still being debated at that time. While more and more scientists believed that most craters were created by impacts, many still believed that at least some of them had to be of volcanic origin. Look at the rubble extending northward of Descartes to the Apollo 16 landing site. Known as the Descartes Highlands, it resembles earthly volcanoes with lava pouring out of a caldera. Likewise, many thought that the Cayley Plains were volcanic in origin. The landing site was carefully chosen after scrutiny of high-resolution images to be sure it was safe despite the treacherous terrain. Apollo 16 landed between two small bright craters known as North Ray and South Ray and used the lunar rover to cover as much ground as possible. No evidence of volcanic flows was found. Instead breccia, a conglomerate of fragmented, sharp shards of rock, was found in abundance. Further evaluation of the fragments within the rocks show most of them to be pieces of more ancient breccia. While it was not directly sampled, the Descartes Highlands is now thought to be ejecta from several lunar impacts. The rest of the landscape consists mostly of ancient craters that predate the Imbrium impact event. Lindsey, Lade, Saunder, and others show severe erosion consistent with their great age. Delambre and Kant are younger but still weathered. Theon Senior and Theon Junior are younger still, but Alfraganus is the only named crater likely to a billion years or less in age. The whole region probably represents original lunar crustal material that has been pulverized by countless impacts over the early eons of the Moon’s existence. This is likely what the areas of the maria looked like before the basin lowlands were excavated by gigantic impacts and then filled with basaltic lava. The Apollo discoveries put another nail in the coffin of the volcanic crater hypothesis and drew attention to neglected, seminal works that had been published more than two decades earlier. Dr. Ralph Baldwin from Grand Rapids, Mich., studied craters produced by explosives during World War II and became interested in lunar craters while lecturing at Adler Planetarium. His discovery that the depth to diameter ratios of the craters fit well on a logarithmic curve generated from his explosives studies led him to publish a paper on the impact origin of lunar craters in Popular Astronomy in 1942. He theorized that impacts of objects traveling at speeds measured in tens of kilometers per second would vaporize as violently and quickly on impact as TNT, causing explosive excavation of craters. Later he published The Face of the Moon in 1949, further detailing his theory for crater formation. The scientific journals of the day were not interested in lunar astronomy, and his work was ignored academically at the time. He published The Measure of the Moon in 1963 and A Fundamental Survey of the Moon in 1965, expanding on his previous works. Apollo explorations and rock samples supported his conclusions as did other lunar studies, and eventually his views were accepted by the rest of the scientific community. He finally received well-deserved recognition in 2000 when he was presented with the Barringer Medal for his studies in impact cratering. It was succinctly noted: “Seldom has one man been so right about so many things so early.” Quadrant 49: Right place for the crater debate — Images and text provided by Howard Eskildsen
55 Sky’s Up I had the privilege of meeting Dr. Baldwin in 2009. Fellow lunar enthusiast Bob O’Connell and I traveled to his home in Naples, Fla. Though he was 97 years old and hard of hearing, he was alert and insightful. He was working on an article about Mare Nectaris for the journal Icarus at the time. We left feeling thrilled and inspired by the visit.
56 Sky’s Up the art of astronomy Astrophotographer Chris Sullivan used an Explore Scientific 208mm Newtonian, Skywatcher AZ-EQ5 mount and a ZWO ASI 1600MM-Cool camera to nab the Pacman Nebula. Formally known as NGC 281, this HII emission nebula is located in the Cassiopeia constellation. For additional technical information, click here. Pacman Nebula Astrophotographer: Christopher Sullivan Sullivan used the same imaging setup for this photograph of the Sunflower Galaxy. Also known as Messier 63, this spiral galaxy is swirling about 27 million light years away in the Canes Venatici constellation. For additional technical details, click here. Sunflower Galaxy
the art of astronomy Astrophotographer: Christopher Sullivan 57 Sky’s Up Sullivan spent four nights in July 2017 imaging the Bubble Nebula, which is an emission nebula in the Cassiopeia constellation. For additional technical details, click here. Bubble Nebula Sullivan used an Explore Scientific 208mm Newtonian, Skywatcher AZ-EQ5 mount and a QHY-CDD 183C Beta camera to get this shot of Thor’s Helmet — an emission nebula located in the Canis Major constellation that is about 30 light years across. For additional technical details, click here. Thor’s Helmet
58 Sky’s Up the art of astronomy Astrophotographer: Steve Siedentop Astrophotographer: Trevor Jones Astrophotographer Trevor Jones took this image of the Trifid Nebula (Messier 20) using an Explore Scientific FPL53 Series 140mm f/6.7 refractor. Located in the Sagittarius constellation, the glowing beauty is a combination of a reddish emission nebula, a blue reflection nebula, a dark nebula and an open cluster of stars. Veil Nebula Astrophotography Steve Siedentop captured the Veil Nebula using an Explore Scientific FPL53 Series 165mm f/7 refractor. Located in the Cygnus constellation, the nebula is divided into three main parts – the Eastern Veil, the Western Veil and Pickering’s Triangle. Trifid Nebula
59 Sky’s Up the art of astronomy Astrophotographer: Jack Newton California Nebula Jack Newton used the Explore Scientific FPL53 Series 165mm f/7 refractor to create this image of the California Nebula, which is an emission nebula located in the Perseus constellation. Astrophotographer Chris Sullivan used an Explore Scientific 208mm Newtonian, Skywatcher AZ-EQ5 mount and a ZWO ASI 1600MM-Cool camera to get this image of HFG1 and Abell 6, which are planetary nebulae in the Cassiopeia constellation. For additional technical information, click here. HFG1 & Abell 6 Astrophotographer: Chris Sullivan
60 Sky’s Up lunar calendar created by Howard Eskildsen
January 15 February 1 February 15 March 1 March 15 April 1 April 15 May 1 May 15 June 1 June 15 July 1 July 15 August 1 August 15 September 1 September 15 October 1 October 15 November 1 November 15 December 1 December 15 January 1 DST Local Time A B B C C D D B C D B C D B C D B C D B C D A B C D A B C D A B C D A B C D A B C D A B C D A C D A C D A B A B A A A A 5 p.m. 6 p.m. 7 p.m. 8 p.m. 9 p.m. 10 p.m. 11 p.m. Midnight 1 a.m. 2 a.m. 3 a.m. 4 a.m. 5 a.m. 6 a.m. 7 a.m. 6 7 8 9 10 11 M 1 2 3 4 5 6 7 8 61 Sky’s Up With a universe of options to explore, it can be difficult to track what awe-inspiring treasures are visible in your sky each month. To help guide your explorations throughout the year, Sky’s Up is providing the following collection of seasonal star maps created by noted celestial cartographer Wil Tirion. Based in The Netherlands, Tirion has been crafting stars maps since the 1970s and became a professional uranographer shortly after the publication of his highly regarded Sky Atlas 2000.0 in 1981. To learn more about Tirion and his work, click here. the key to your sky created by Wil Tirion
E C L I P T I C Horizon 10°N Horizon 20°N Horizon 30°N nozir oH N°03 zir oH 2 no N°0 zir oH no °01 N SOUTH WEST EAST NORTH WINTER SKY For observers at 10° to 30° northern latitudes A ANDROMEDA ANTLIA ARIES AURIGA CAELUM CAMELOPARDALIS CANCER CANES VENATICI CANIS MAJOR CANIS MINOR CARINA CASSIOPEIA CEPHEUS CETUS COLUMBA COMA BERENICES CRATER DORADO DRACO ERIDANUS FORNAX GEMINI HOROLOGIUM HYDRA HYDRUS LACERTA LEO LEO MINOR LEPUS LYNX MENSA MONOCEROS ORION PEGASUS PERSEUS PHOENIX PICTOR PISCES PUPPIS PYXIS RETICULUM SCULPTOR SEXTANS TAURUS TRIANGULUM URSA MAJOR URSA MINOR VELA VOLANS Adhara Achernar Alphard Betelgeuse Canopus Capella Castor Pollux Polaris Procyon Regulus Rigel Sirius Algol Mira M31 M42 M41 Tarantula Nebula M35 M44 Hyades Pleiades Double Cluster LMC 62 Sky’s Up the key to your sky created by Wil Tirion
E C L I P T I C Horizon 40°N Horizon 50°N Horizon 60°N 06 nozir oH N° 5 nozir oH N°0 nozir oH N°04 SOUTH WEST EAST NORTH WINTER SKY For observers at 40° to 60° northern latitudes A BOOTES ANDROMEDA ANTLIA ARIES AURIGA CAELUM CAMELOPARDALIS CANCER CANES VENATICI CANIS MAJOR CANIS MINOR CASSIOPEIA CEPHEUS CETUS COLUMBA COMA BERENICES CORONA BOREALIS CYGNUS DRACO ERIDANUS FORNAX GEMINI HERCULES HOROLOGIUM HYDRA LACERTA LEO LEO MINOR LEPUS LYNX LYRA MONOCEROS ORION PEGASUS PERSEUS PISCES PUPPIS PYXIS SEXTANS TAURUS TRIANGULUM URSA MAJOR URSA MINOR Adhara Alphard Aldebaran Betelgeuse Capella Castor Pollux Deneb Polaris Procyon Regulus Rigel Sirius Vega Algol Mira M31 Double Cluster M42 M35 M41 M44 M13 Hyades Pleiades 63 Sky’s Up the key to your sky created by Wil Tirion
E C L I P T I C Horizon 10°N Horizon 20°N Horizon 30°N nozir oH N°03 nozir oH N°02 ozir oH N°01 n SOUTH WEST EAST NORTH SPRING SKY For observers at 10° to 30° northern latitudes B BOOTES ANTLIA AURIGA CAMELOPARDALIS CANCER CANES VENATICI CANIS MAJOR CANIS MINOR CARINA CASSIOPEIA CENTAURUS CEPHEUS CHAMAELEON CIRCINUS COLUMBA COMA BERENICES CORONA BOREALIS CORVUS CRATER CRUX CYGNUS DRACO GEMINI HERCULES HYDRA LEO LEO MINOR LIBRA LUPUS LEPUS LYNX LYRA MONOCEROS MUSCA NORMA OPHIUCHUS ORION PERSEUS PUPPIS PYXIS SCORPIUS SER SERPENS CAPUT SEXTANS TAURUS TRIANGULUM AUSTRALE URSA MAJOR URSA MINOR VELA VIRGO VOLANS Adhara Alphard Antares Hadar Acrux Arcturus Betelgeuse Capella Castor Pollux Polaris Procyon Regulus Rigil Kent Sirius Vega Spica Mimosa Double Cluster M35 M44 M41 M13 Southern Pleiades Eta Carinae Nebula Omega Centauri Jewel Box 64 Sky’s Up the key to your sky created by Wil Tirion
B Horizon 40°N Horizon 50°N Horizon 60°N 6 nozir oH N°0 5 nozir oH N°0 04 nozir oH N° SOUTH WEST EAST NORTH SPRING SKY For observers at 40° to 60° northern latitudes BOOTES ANDROMEDA ANTLIA AQUILA ARIES AURIGA CAMELOPARDALIS CANCER CANES VENATICI CANIS MAJOR CANIS MINOR CASSIOPEIA CENTAURUS CEPHEUS COMA BERENICES CORONA BOREALIS CORVUS CRATER CYGNUS DRACO GEMINI HERCULES HYDRA LACERTA LEO LEO MINOR LIBRA LYNX LYRA MONOCEROS OPHIUCHUS ORION PEGASUS PERSEUS PUPPIS PYXIS SAGITTA SCORPIUS SERPENS CAPUT SEXTANS TAURUS TRIANGULUM URSA MAJOR URSA MINOR VELA VIRGO VULPECULA Alphard Aldebaran Arcturus Betelgeuse Capella Castor Pollux Deneb Polaris Procyon Regulus Sirius Vega Spica Algol M31 Double Cluster M35 M44 M13 Hyades Pleiades 65 Sky’s Up the key to your sky created by Wil Tirion
E C L I P T I C Horizon 10°N Horizon 20°N Horizon 30°N zir oH N°03 no zir oH N°02 no ozir oH N°01 n SOUTH WEST EAST NORTH SUMMER SKY For observers at 10° to 30° northern latitudes C BOOTES ANDROMEDA APUS AQUARIUS AQUILA ARA CAMELOPARDALIS CANES VENATICI CAPRICORNUS CASSIOPEIA CENTAURUS CEPHEUS CIRCINUS COMA BERENICES CORONA AUSTRALIS CORONA BOREALIS CORVUS CYGNUS DELPHINUS DRACO EQUULEUS GRUS HERCULES HYDRA INDUS LACERTA LEO LEO MINOR LIBRA LUPUS LYRA MICROSCOPIUM NORMA OPHIUCHUS PAVO PEGASUS PERSEUS PISCES PISCIS AUSTRINUS SAGITTA SAGITTARIUS SCORPIUS SCUTUM SERPENS CAUDA SERPENS CAPUT TELESCOPIUM TRIANGULUM AUSTRALE TUCANA URSA MAJOR URSA MINOR VIRGO VULPECULA Altair Antares Hadar Arcturus Fomalhaut Polaris Rigil Kent Vega Spica Deneb M31 Double Cluster M13 M7 M8 M22 Omega Centauri 66 Sky’s Up the key to your sky created by Wil Tirion
E C L I P T I C C Horizon 40°N Horizon 50°N Horizon 60°N oH zir no N°06 r oH nozi N°05 zir oH N°04 no SOUTH WEST EAST NORTH SUMMER SKY For observers at 40° to 60° northern latitudes BOOTES ANDROMEDA AQUARIUS AQUILA ARA ARIES AURIGA CAMELOPARDALIS CANCER CANES VENATICI CAPRICORNUS CASSIOPEIA CEPHEUS COMA BERENICES CORONA AUSTRALIS CORONA BOREALIS CYGNUS DELPHINUS DRACO EQUULEUS GEMINI HERCULES HYDRA LACERTA LEO LEO MINOR LIBRA LUPUS LYNX LYRA MICROSCOPIUM NORMA OPHIUCHUS PEGASUS PERSEUS PISCES PISCES SAGITTA SAGITTARIUS SCORPIUS SCUTUM SERPENS CAUDA SERPENS CAPUT TELESCOPIUM TRIANGULUM URSA MAJOR URSA MINOR VIRGO VULPECULA Altair Antares Arcturus Capella Castor Pollux Deneb Polaris Vega Spica Algol M31 Double Cluster M13 M7 M8 M22 67 Sky’s Up the key to your sky created by Wil Tirion
E C L I P T I C Horizon 10°N Horizon 20°N Horizon 30°N Hor zi on 30 N° Hor zi on 2 °0 N Hor zi no 01 N° SOUTH WEST EAST NORTH AUTUMN SKY For observers at 10° to 30° northern latitudes D ANDROMEDA AQUARIUS AQUILA ARIES AURIGA CAMELOPARDALIS CAPRICORNUS CASSIOPEIA CEPHEUS CETUS CORONA AUSTRALIS CYGNUS DELPHINUS DORADO DRACO EQUULEUS ERIDANUS FORNAX GEMINI GRUS HERCULES HOROLOGIUM CAELUM HYDRUS INDUS LACERTA LEPUS LYNX LYRA MICROSCOPIUM OCTANS OPHIUCHUS ORION PAVO PEGASUS PERSEUS PHOENIX PISCES PISCIS AUSTRINUS RETICULUM SAGITTA SAGITTARIUS SCULPTOR SCUTUM SERPENS TAURUS CAUDA TELESCOPIUM TRIANGULUM TUCANA URSA MAJOR URSA MINOR VULPECULA Achernar Aldebaran Altair Betelgeuse Capella Deneb Fomalhaut Polaris Rigel Vega Algol Mira M31 Double Cluster M42 M35 M13 M8 M22 SMC 47 Tuc Hyades Pleiades 68 Sky’s Up the key to your sky created by Wil Tirion
E C L I P T I C Horizon 40°N Horizon 50°N Horizon 60°N oH ir oz n 06 N° oH ir oz n 05 N° oH ir oz n 04 N° SOUTH WEST EAST NORTH AUTUMN SKY For observers at 40° to 60° northern latitudes D BOOTES ANDROMEDA AQUARIUS AQUILA ARIES AURIGA CAMELOPARDALIS CANCER CANES VENATICI CAPRICORNUS CASSIOPEIA CEPHEUS CETUS CORONA BOREALIS CYGNUS DELPHINUS DRACO EQUULEUS ERIDANUS FORNAX GEMINI GRUS HERCULES LACERTA LEO MINOR LYNX LYRA MICROSCOPIUM OPHIUCHUS ORION PEGASUS PERSEUS PHOENIX PISCES PISCIS AUSTRINUS SAGITTA SAGITTARIUS SCULPTOR SCUTUM SERPENS CAUDA TAURUS TRIANGULUM URSA MAJOR URSA MINOR VULPECULA Aldebaran Altair Betelgeuse Capella Castor Pollux Deneb Fomalhaut Polaris Vega Algol Mira M31 Double Cluster M35 M13 Hyades Pleiades 69 Sky’s Up the key to your sky created by Wil Tirion
parting shot 70 Sky’s Up COURTESY OF NASA/JPL-Caltech/MSSS This May 11, 2016, self-portrait of NASA’s Curiosity Mars rover shows the vehicle at the Okoruso drilling site on lower Mount Sharp’s “Naukluft Plateau.” The scene is a mosaic of multiple images taken with the arm-mounted Mars Hands Lens Imager.